NeilM - my Roadster has a red terminal block in the live feed next to the battery. I just can't remember if it's a fuse or not.
Note to self - spend a bit more time on the Roadster......
meabh - thanks for that - I'll keep a watch, because until I've put some miles on it I won't know for sure whether I've got it sorted.
Nigel - totally agree - all circuit diagrams should be available - including relay functions.